Field of the Invention
This invention relates to illumination and display fields, and in particular, it relates to a light emitting device and a projection system.
Description of Related Art
As television and other display apparatus are adopting high resolutions and large sizes, their requirements for brightness of the light source increase. In particular, for special applications such as cinema projection systems, light sources up to ten thousand lumens are often required.
To achieve high brightness light sources, conventional technologies use array light sources formed by arrayed light emitting elements, and compress the output light of the array light source to increase brightness. For example, FIG. 1 illustrates a light emitting device according to a conventional technology. As shown in FIG. 1, the light emitting device includes a laser array light source 110, a collimating lens array 120, a focusing lens 130, a light homogenizing rod 140, a lens 150, and a phosphor wheel 160. FIG. 2 is a right side view of the laser array light source of FIG. 1. As shown in FIG. 2, the laser array light source is formed by multiple laser diodes forming an array. The laser array light source has a high power and can emit high brightness laser light. The collimating lens array 120 includes multiple collimating lens units, each collimating lens unit corresponding to a laser diode, to collimate the light emitted by the laser diode. To reduce the cross section of the light beam, the focusing lens 130 focuses the output light of the collimating lens array 120. The focused light is homogenized by the light homogenizing rod 140, and is them focused by the lens 150 onto the phosphor wheel 160 to generate a desired converted light.
However, because the focal length of the focusing lens 130 is relatively long, the length of the entire light emitting device is long, and its size is large.